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Drug Interactions between ivermectin and nirmatrelvir / ritonavir

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

ritonavir ivermectin

Applies to: nirmatrelvir / ritonavir and ivermectin

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of ivermectin and the risk of adverse effects. The proposed mechanism, based on in vitro data, is decreased clearance due to inhibition of CYP450 3A4, the primary isoenzyme responsible for the metabolic clearance of ivermectin.

MANAGEMENT: Caution is advised when ivermectin must be used concomitantly with potent CYP450 3A4 inhibitors. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate whenever a potent CYP450 3A4 inhibitor is added to or withdrawn from therapy.

References (2)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Zeng Z, Andrew NW, Arison BH, Luffer-Atlas D, Wang RW (1998) "Identification of cytochrome P4503A4 as the major enzyme responsible for the metabolism of ivermectin by human liver microsomes." Xenobiotica, 28, p. 313-21

Drug and food interactions

Moderate

ritonavir food

Applies to: nirmatrelvir / ritonavir

ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.

MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.

References (1)
  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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